The present invention relates to an improved transmission gear box adapted particularly for a miniature motor, which is characterized in its simple structure, ready assembly to a miniature motor and easy production thereof and provided with a round plate and a cap that are easily snapped together. The round plate having a central through hole disposed at the center thereof and a pair of oval shaped through holes are located at the opposite sides of the center hole respectively is secured to the output end of a mininature motor with the shaft of the motor sticking out of the central through hole of the round plate with a gear disposed at the end of the same. A transmission gear set is operably disposed on top of the round plate. The periphery of the round plate is provided with a number of protrusions or recesses that can be in snapping engagement with the corresponding recesses or protrusions disposed on the periphery of the bottom of the cap with the transmission gear set housed therein.
A conventional transmission gear box, as shown in FIGS. 1, is mainly comprised of a miniature motor 1A, a gear set 5A, a base board 51A, an upper cap 6A and a positioning plate 7A. The base board 51A is provided with a number of recessed cuts 510 A on the periphery thereof which are engaged with a number of corresponding protrusion spots 610 A disposed on the inner periphery of the bottom of the upper cap 6A so as to permit the upper cap 6A to be engaged with the base board 51A.
This prior art has the following disadvantages in the production and use:
1. There are many redundant parts used, such as the motor lid 11A and the base board 51A which serves as the base of the transmission gear box, and the production and assembly thereof are relatively difficult.
2. The protrusion spots of the upper cap and the recessed cuts disposed on the periphery of the base board are not engaged with each other firmly; and the riveting process can cause a high rate of defective products.
3. This kind of engagement is not secure enough, resulting in the disengagement of the upper cap and the base board due to the vibration of the miniature motor.
4. The base board and the motor lid are produced as two separate parts, making the production procedure redundant and the cost thereof high.
To make an improvement on the prior art transmission gear box, the present inventor developed a gear box for a miniature motor which is simple in structure, easy to assemble and secure in engagement.